He also spoke about how, unlike the other four Great Lakes, Lake Erie is surrounded by agriculture and a more urbanized landscape.

You can listen to him speak about his "50 and 2 Rule" here:

Lake Erie has seen a resurgence in blooms of cyanobacteria (sometimes referred to as blue-green algae) over the last ten years. It was once a big problem in the 60s and 70s, and it has returned as a problem again.